Since its first introduction, the method of playing golf, playing equipment, and playing rules have been refined to a great degree. One area of refinement has been in the development of specific postural positioning, such as in the development of stances and grips, in order to increase the effectiveness of the golf swing. Postural positioning may vary in accordance with a selected club being used, the distance in which the ball is to be driven, and the playing environment.
To successfully master the art of playing golf, one must be proficient in initially driving the ball off the tee, positioning the ball on the green, and putting the ball into the hole. Normally, a wood is used for driving the ball, a putter is used for putting the ball, and an iron is used for most intermediate strokes required to position the ball on the green. A myriad of wood and iron clubs have been developed in order to provide for a relatively fine adjustment of the strokes to be achieved.
A given set of golf clubs includes a plurality of numbered wood and iron clubs as well as a pitching wedge, a sand wedge and a putter. The wood clubs may range in number from one to seven and the irons typically range in number from one to nine. Each club includes shaft and a head defining a face. The lower numbered clubs have longer shafts and the higher numbered clubs have shorter shafts. The face of each club is inclined rearwardly to the vertical axis of the shaft in a direction of the movement of the head of the club when being swung. The value of the angle of the face with respect to the vertical axis of the shaft, that is, the loft angle, increases with an increase in the number of the club or as the shaft length decreases, the sand wedge having the highest loft angle value. The smaller the loft angle, the lower the loft of the ball and the greater the run of the ball after subsequent contact with the ground.
For any set of golf clubs, it is important that the swing of each club be consistent. However, even when golf clubs are swung consistently, the loft changes at impact due to centrifugal forces. Prior art teaches that this tendency to change the loft can be compensated for by providing a set of golf clubs which have progressively decreasing offsets, beginning with the lower numbered clubs and progressively decreasing toward the higher numbered clubs. The offset is the distance between the central axis of the club shaft and the bottom leading edge of the club face. For the most part, the leading edge of the club face actually trails the shaft axis of the clubs having longer shafts and the leading edge of the club face actually precedes the shaft axis of the clubs having shorter shafts. The offset is related to the distance by which the center of the mass of the club head trails the axis of the shaft. Because of the offset and the related position of the center of mass, the centrifugal forces that result about the center of mass of the head, when the club is swung, tend to cause the club to increase its loft angle as the shaft bends. By progressively varying the offset from the lower numbered clubs to the higher numbered clubs, an appropriate degree of consistent loft change can be achieved from club to club.
Golf club sets having clubs with offset club faces are well known in the prior art. For example, U.S. Pat. No. 3,966,210, issued Jun. 29, 1976 to John J. Rozmus, shows two distinct golf club heads each having an offset club face. The leading edge of the ball striking face of each club head is offset so as to precede the vertical axis of the shaft in a direction of the movement of the head of the club when being swung. Another iron golf club set is shown in U.S. Pat. No. 4,986,541, issued Jan. 22, 1991 to Mitsutake Teramoto et al., wherein the set comprises a plurality of iron clubs having different left angles between the face of the golf club head and the axis of the shaft of the club. At least some of the clubs in the set have face progression values which are reduced consecutively or in steps in accordance with a decrease in the number of the iron or a decrease in the value of the loft angle. Two other patents of some relevance to the instant invention are U.S. Pat. Nos. 4,754,969, issued Jul. 5, 1988 to Masashi Kobayashi and 4,895,367, issued Jan. 23, 1990 to Ryota Kajita et al.
Teramoto discloses an iron golf club set comprising a plurality of iron clubs having face progression values which are increased in accordance with an increase in the value of the club number (i.e., the left angle). Teramoto only discloses a plurality of iron clubs having face progression values which are increased in accordance with an increase in the value of the club number. Teramoto makes no mention of decreasing the face progression values for wood golf clubs with increasing club numbers. Kobayashi applies the same teaching to both wood and iron clubs. Neither Kobayashi nor Teramoto discloses a set of wood golf clubs with face progression values that decrease as the progressive wood club numbers increase. While Kajita et al. define a range of values for the offset "y," the reference teaches away from selecting a pattern of offsets as in the present invention. At column 3, lines 62-63, Kajita et al. disclose "all the clubs of such a golf club [set] have a feeling close to that of irons." In column 3, line 67 through column 2, line 4, Kajita et al. expressly state that "it is possible also to set y of the iron clubs so as to be in accordance with the feeling of the conventional wood clubs." Therefore Kajita et al. specifically teach that one would select offset progressions which are modeled after a conventional club set so that the woods match the offsets of a set of irons, or vice versa, with the offset value increasing as the number of the club increases.
The present invention uses offsets which are contrary to those taught by Kajita et al., with the offset or "face progression value" of Applicant's woods decreasing as the wood numbers increase. The face progression values for the woods herein are the opposite of those disclosed by Kajita et al., Koboyashi, and Teramoto et al. The offsets of the instant invention uniquely allow the golfer to use a single swing to produce a sweeping motion with the woods, a down and through motion with the higher numbered irons, and a combination swing with the lower numbered irons. Through the use of the offsets of the instant invention, the head of the golf club will be properly positioned relative to the hands of the user at the point of impact based on a single swing. With the conventional offsets taught by Kajita et al., the golfer must adjust his swing for the longer or shorter irons to have the proper hand positioning with each club at the point of impact. Therefore, the teachings of Kajita et al. wherein the woods emulate the irons or vice versa is insufficient to enable one skilled in the art to arrive at a solution to the problem which forms the basis of the present invention.
All of the problems associated with achieving a timely impact of the golf club with the ball have yet to be addressed. A golf club set which offers a variation in face progression values including face progression plus values, zero values, and minus values would meet the needs to achieving a timely impact of the golf club with the ball. Applicant proposes a golf club set having such a variation in face progression values. None of the above noted patents, either singly or in combination, are seen to disclose the specific arrangement of concepts disclosed by applicant with respect to the present invention.